TOTP stands for Time-based One-time Password, which is a type of OTP that is generated based on two pieces of information: time and seed. The time is the current timestamp that is synchronized between the client and the server. The seed is a secret key that is shared between the client and the server. The TOTP algorithm combines the time and the seed to generate a unique and short-lived OTP that can be used for two-factor authentication.

REST API is a feature that allows FortiAuthenticator to integrate with an existing identity management system with the goal of authenticating and deauthenticating users into FSSO. REST API stands for Representational State Transfer Application Programming Interface, which is a method of exchanging data between different systems using HTTP requests and responses. FortiAuthenticator provides a REST API that can be used by external systems to perform various actions, such as creating, updating, deleting, or querying users and groups, or sending FSSO logon or logoff events.

A SAML metadata file can be used to import the required IDP configuration for SAML service provider mode. A SAML metadata file is an XML file that contains information about the identity provider (IDP) and the service provider (SP), such as their entity IDs, endpoints, certificates, and attributes. By importing a SAML metadata file from the IDP, FortiAuthenticator can automatically configure the necessary settings for SAML service provider mode.

Realms are a way to delegate user accounts, user groups and permissions per domain when they are authenticating on a single FortiAuthenticator device. A realm is a logical grouping of users and groups based on a common attribute, such as a domain name or an IP address range. Realms allow administrators to apply different authentication policies and settings to different groups of users based on their realm membership.

Two statements about the self-service portal are true:
Self-registration information can be sent to the user through email or SMS using the notification templates feature. This feature allows administrators to customize the messages that are sent to users when they register or perform other actions on the self-service portal.
Realms can be used to configure which self-registered users or groups can authenticate on the network using the realm-based authentication feature. This feature allows administrators to apply different authentication policies and settings to different groups of users based on their realm membership.